The ability of growth hormone (GH) to increase milk yield through somatomedins is well characterized,however recent studies utilizing mammary epithelial cell (MEC) lines have indicated a possible direct effecton MEC. In the mammary alveolar cell-T (MAC-T) line, relative abundance of mRNA for two milk protein genes, α-lactalbumin and αS1-casein, and GH receptor was increased by GH. MAC-T cells were compared tobovine mammary tissue explants and primary MEC isolated from raw milk through culture in classicallactation medium (dexamethasone, insulin, prolactin) with 0 or 10 ng/mL GH. Explant and primary cellmRNA abundance showed a similar pattern to MAC-T indicating that the effects observed in cell lines maybe relevant in vivo. To begin to understand the nature of the effects of GH in MEC, global protein expressionin MAC-T cells was analyzed by 2-D gel electrophoresis, finding the abundance of 40 proteins altered byinclusion of 10ng/mL GH. Proteins were identified using MALDI-TOF with tandem MS and include enzymesinvolved in glycolysis, lipogenesis, protein processing and transport.


Animal Sciences



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